This invention relates to a improved driving device for the traction of cables or chains, usable in particular to drive electric anchor winches, electric winches or windlasses.
Anchor winches are used to operate the anchors of boats and ships; they may be of the vertical-axis (capstan) or horizontal-axis (windlass) type, and are usually driven by an electric or hydraulic motor. The chain or cable is wound for about half a turn round the “wildcat” of the winch and then descends into the chain locker; in addition to the wildcat, the motor activates a barrel designed to operate the cables, which is positioned on the same axis as the wildcat in the case of capstan winches and on an axis with equal or faster rotation in the case of windlasses.
The wildcat is connected to the drive shaft by a mechanical coupling, the insertion of which is facilitated by a clutch; in order to control the movement of the wildcat when it remains idle, a band brake is fitted to reduce the descent speed of the anchor and cut off the motor, if necessary.
In addition, the direction of rotation of the motor can always be reversed and, in the case of windlasses, the anchors can even be operated one at a time, by uncoupling the wildcat of the anchor which is not to be moved, and locking it with the brake. Winches are usually proportioned to weigh the two anchors simultaneously and break out (release from the sea bed, by reference to a conventional depth of two chain shackles) one anchor at a time. Anchor winches are usually driven by electric motors, commonly regulated by the Ward-Leonard system, electronic systems or the like, in order to reduce speed at the time of breaking out.
Alternatively, purely electric winches are used for traction which are fitted with a directly coupled electric motor that forms a single assembly with the winch. In this case, coupling for low powers is effected by mounting a sprocket wheel on the drive shaft, while for high powers, a flexible coupling is fitted, the outer band of which acts as a brake pulley; the direction is reversed by automatic control or remote controls using contactors.
The operating mechanism of each winch comprises a set of safety devices (ratchet gears, automatic brakes) which prevent spontaneous rotation and unwinding of cables or chains under the action of the load when the drive action ceases.
In any event, the electrical circuit which powers conventional winches is always complex, especially because the battery of the boat, which is normally located dozens of metres from the anchor winch, needs to be connected both to the winch motor (electric or hydraulic) and to its drive relays.
In addition, as ancillary drive controls (such as a lever or pedal control) are generally used, together with other service devices (length sensors and pushbutton panels with length counters) and emergency devices, the installation of the entire electrical operating circuit obviously becomes increasingly complicated due to the large number of connection cables and the special features of the various connections to be made.